(a) Technical Field
The present invention relates to an aerodynamic control system for vehicles, more particularly, to an aerodynamic control system for vehicles which may improve aerodynamic performance of a traveling vehicle and increase fuel efficiency and driving stability of the vehicle.
(b) Description of the Related Art
As is generally known, when a vehicle is in motion, a front part of a vehicle frame pushes air in the upward, downward, leftward and rightward directions, and the pushed air moves to the rear part of the vehicle frame and returns to its original position.
It takes a period of time for such air to return to its original position and, as the time increases, a vacuum region formed at a rear part of the vehicle increases.
Here, the generated vacuum pulls the vehicle frame at the back, and thus the vehicle meets with air resistance. Further, a lift, in which the vehicle is lifted when the vehicle travels at a high speed, is generated due to a vortex generated by the vacuum.
In order to prevent such a lift, driving stability needs to be achieved when the vehicle travels at a high speed through wake control to improve aerodynamic performance and vortex control at the rear part of the vehicle.
In order to improve aerodynamic performance of the vehicle, wake control is very important. In order to make a wake state which is advantageous in aerodynamic performance during driving of the vehicle, air introduced into a lower part of the vehicle should be efficiently exhausted to the rear part of the vehicle through a lower part of a rear bumper or a lower end of the rear bumper.
In order to control the wake of the vehicle, the ground clearance of the lower end of the rear bumper may be increased, a slit hole may be applied to the lower end of the rear bumper, and a diffuser may be applied to a rear end of the vehicle frame so as to improve a flow diffusion angle.
FIG. 1 (RELATED ART) is a view illustrating an air flow state of the lower part of a vehicle to improve aerodynamic performance of the vehicle. As exemplarily shown in FIG. 1, air introduced into the lower part of the vehicle may be smoothly exhausted in the backward direction by increasing the ground clearance of the lower end of a rear bumper, and an air flow diffusion angle at the rear end of a vehicle frame may be increased through increase in the ground clearance, thereby improving a wake.
However, an increase in the ground clearance of the lower end of the rear bumper causes a large region of the lower part of the vehicle frame to be exposed from a rear position of the vehicle and is thus disadvantageous in terms of the exposure (visible amount) of the lower part of the vehicle.
Therefore, vehicle manufacturers set up a standard to minimize the visible amount of the lower part of a vehicle at a driver's eye height H of a rear vehicle, as exemplarily shown in FIG. 2 (RELATED ART), and an increase in the ground clearance of the lower end of the rear bumper is limited in improving aerodynamic performance of the vehicle due to increase in the visible amount of the lower part of the vehicle and design limitations.
FIG. 3 (RELATED ART) is a view illustrating an example in which a slit-shaped hole 2 is applied to the lower end of a rear bumper. As exemplarily shown in FIG. 3, if the slit-shaped hole 2 is formed at the lower end of a rear bumper 1, air introduced into the lower part of a vehicle may be smoothly exhausted to an area in the rear of the vehicle through the hole 2.
Application of such a hole 2 is advantageous in terms of the visible amount of the lower part of the vehicle and advantageous in terms of production costs, as compared to installation of a diffuser. However, since the hole 2 is always visible, application of the hole 2 is disadvantageous in terms of vehicle design, and the effect on aerodynamic performance generated by the hole 2 is minimal.
Further, in the case of a flap-type active rear diffuser, when a vehicle travels at a high speed, a flow diffusion angle may be controlled according to operation of a diffuser flap at the lower end of a rear bumper, but the diffuser flap moves based on the lower end surface of a conventional bumper, and thus an increase in the flow diffusion angle is restricted.